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Feb 8th-9th Obs/Discussion Thread


mappy

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No disrespect to LWX, but something doesn't seem right when their maps for max snowfall and most likely range look almost identical (at least north of I-70).

 

I think 3-6" would be a safer call for the northern counties at this point than 6-9"... there's still uncertainty and there'd be more room to adjust higher or lower when things look more clear.

Their numbers have come down a bit already. They're forecasting more snow than the Euro has shown at best run lately so they are running to the top end.

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Such a contrast to the RGEM, too...when considering meso models.  Is the NAM actually a sort of low-end outlier now?  The other day it was more in line with other models and the GFS was on the relative high end.  Now almost all other guidance trended (last night) to a better event and the NAM goes the other way (or stands its ground, more like).  Ugh!

 

The NAM is not a very skilled model for winter weather.  We use it more because it is available rather than it being useful.  If the NAM didn't exist, our collective level of forecasting skill in the winter wouldn't diminish one iota.

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No disrespect to LWX, but something doesn't seem right when their maps for max snowfall and most likely range look almost identical (at least north of I-70).

I think 3-6" would be a safer call for the northern counties at this point than 6-9"... there's still uncertainty and there'd be more room to adjust higher or lower when things look more clear.

Looks like the most likely is close to the max because they are leaning the official forecast toward the wetter and colder solutions. Problem with mesoscale banding is that it's narrow and hard to predict but those areas that get in them can really dump. Higher forecast to account for this.

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I think it's a real difficult setup. A lot of factors coming together.

 

It most definitely is.  As I said the other day, I do not envy anyone on the hot seat having to make a decision.  This has all the makings of doing the best one can in terms of a forecast, and with this setup there's almost a guarantee there will be some very upset people who either expected a lot of snow and got much less, or vice-versa.  Not fun.

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The NAM is not a very skilled model for winter weather.  We use it more because it is available rather than it being useful.  If the NAM didn't exist, our collective level of forecasting skill in the winter wouldn't diminish one iota.

Though this isn't really a nor'easter and an area it might have more skill than normal given it's sort of a convective enhanced small band feature.

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Ah, okay! Again, forgive me for asking, but is it normal for there to be this much discrepancy between the models within 24-36 hours of an event?  It seemed like the last storm was locked down in advance (though there were jumps in totals and that was a completely different type of system, no?)

 

Small mesoscale events like this are incredibly hard for NWP to get right. The smallest shift can cause very large differences in sensible wx. Inverted trough events are notorious for booms, busts, and unexpected results. Even in real time. 

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I'm throwing in the towel for DC - good luck to the jackpotters in NE MD and Philly....

 

I'm about to throw in the towel on making any kind of reasonable guess on what the outcome will be! :lol:  Other than northeast MD being in the jackpot one way or another (and however much it may be), I really wouldn't know what to say outside that.

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Though this isn't really a nor'easter and an area it might have more skill than normal given it's sort of a convective enhanced small band feature.

 

You'd think so.  It very well could be right.  At the least it is there as a cautionary tale and so it does serve some purpose.  I think it is outside of its range still.  

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You'd think so.  It very well could be right.  At the least it is there as a cautionary tale and so it does serve some purpose.  I think it is outside of its range still.  

I wouldn't hug it but the snowlovers give it a bad rap because they use it wrong mostly. Not to mention most people tend to run snowy here heh. :P

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The NAM is not a very skilled model for winter weather. We use it more because it is available rather than it being useful. If the NAM didn't exist, our collective level of forecasting skill in the winter wouldn't diminish one iota.

this is so true and sad. Ncep needs to work on creating a better short range tool to replace the nam and srefs. The Sref actually are a great idea. Short range high res ensemble but the wild unreliability of the arw members make it useless many times. Between the rap hrrr and suck we have the now cast stuff covered but there is a need in the 24-48 hour window that something like the nam could fill if it wasn't crap.
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Greetings, Quaker! :D

 

And ahh, gotcha! So which model seems to be the one that is handling this system the best? Or will it likely be a nowcasting -type thing?

This system is a fairly small mesoscale event which can be prone to last minute changes up until game time.  Personally, I think that RGEM has been a fairly reliable model within 36-48 hours of snow events over the last couple of years.  I'd keep an eye out on that model today.

 

MDstorm

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Greetings, Quaker! :D

 

And ahh, gotcha! So which model seems to be the one that is handling this system the best? Or will it likely be a nowcasting -type thing?

 

Hmmm, kind of tough to say right now, get back to us on Wednesday and we'll have a definite answer! ;)  Seriously though, the transfer of the low to the coast hasn't happened yet, so I don't think it's possible to say which one is necessarily handling it best.  However, one could argue which ones are handling things more consistently, I suppose.  In which case, some combination of the GFS/GGEM/RGEM/Euro from what I've seen and read in here.  Though the NAM has been somewhat consistent in being the lightest (at least in the metro DC area and around there), but it's gone all over the place too.

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I wouldn't hug it but the snowlovers give it a bad rap because they use it wrong mostly. Not to mention most people tend to run snowy here heh. :P

 

We get pretty twisted around about model skill in here because of all the government folks and their tendency to 1) understandably want to use their own models, and 2) our collective reluctance to criticize the american models.  Sometimes I think the SNE guys are better off.  Nothing needs to be sugarcoated.  They know the Euro is the best model and there is no need to dance around it.  They know the GFS does not handle east coast snowstorms as well.  And they know the NAM sucks for winter weather and don't take it seriously, even if it is right some of the time.  

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NAM is like your crazy drunk Uncle......mostly good for a laugh or 2 and usually just leaves you shaking your head.

BTW------greetings from a fellow Penn Quaker (several years removed :thumbsup: ).

MDstorm

For years I have relied on the globals for placement of features and mostly only use the nam and high res models to help with what the meso scale feature within the system may look like. In this case the nam is way off with the location of the norlun trough so I defer to the gfs/euro/rgem placement that all look similar. Nam can give us a clue what the banding potential within that may be but I wouldn't use it to place features when it's divergent from most guidance.
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